Pump nozzle injection systems or pump-line-nozzle injection systems are used in direct injection internal combustion engines. I valves (inwardly opening valves) characterized by a high operating stability may be used in these fuel injection systems. In addition to a high operating stability, shaping of the injection characteristic is also important in order to optimize the course of combustion in the combustion chamber of an engine with regard to formation of carbon black and HC.
European Patent Application No. 823 549 describes an injector. This injector includes an injector body and a nozzle needle displaceably accommodated in the injector body. The nozzle needle is pressed into its seat by a closing spring. A fuel supply line is provided for supplying fuel to the nozzle needle in the area of a conical face so that a force is directed against the action of the closing spring. The connection between the fuel supply line and a drain to the low-pressure area of the fuel injector is controlled by using a drain valve. The fuel pressure in a control space, which is defined in part by an area of the nozzle needle or a component accommodated thereon, is controlled by using a control valve. The nozzle needle or the component accommodated on it is oriented so that a force acting on the nozzle needle is generated at a high pressure level in the control space, supporting the force of the closing spring. The drain valve and the control valve are controlled by an electromagnetic actuator which is designed as a component. The control valve and the end face of the nozzle needle or the component cooperating with it (e.g., a push rod or the like) which form a part of the control space are dimensioned so that the control valve is pressure balanced at all times.
According to this implementation, the drain valve and the control valve are arranged in series on both sides of an electromagnetic actuator, the lifts of the control valve and drain valve being produced simultaneously by the electromagnetic actuator, and independent triggering of the two valves connected in series is impossible.